368 research outputs found

    A new impedance matching method for an ultra-wide band and dual circularly polarised feed

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    In traditional antenna design, metal components are not placed in the central part of the antenna as they change the characteristics of near field radiation. However, we show that placing a metal ring in the centre of the strip lines, which connect the ends of folded high-frequency dipoles, does not damage the performance of the feed. Instead it significantly improves the voltage standing wave ratio of the feed whilst other performance indicators are not compromised. Thus, our findings show an excellent way of improving the wide band feed. Based on this foundation, a new circularly polarised feed for operation between 0.4 to 2 GHz is introduced for the Chinese Spectral Radioheliograph in this paper. The issue of a feed impedance matching network is investigated. By optimising the impedance matching, the performance of the feed is enhanced with respect to the previous realisations of the Eleven feed. The simulation and experimental results show that the gain of the feed is about 10 dBi, and the VSWR is less than 2:1. In addition, the feed has a low axial ratio, fixed phase centre location, and constant beam width in the range of 0.4 to 2 GHz

    Device modeling of superconductor transition edge sensors based on the two-fluid theory

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    In order to support the design and study of sophisticated large scale transition edge sensor (TES) circuits, we use basic SPICE elements to develop device models for TESs based on the superfluid-normal fluid theory. In contrast to previous studies, our device model is not limited to small signal simulation, and it relies only on device parameters that have clear physical meaning and can be easily measured. We integrate the device models in design kits based on powerful EDA tools such as CADENCE and OrCAD, and use them for versatile simulations of TES circuits. Comparing our simulation results with published experimental data, we find good agreement which suggests that device models based on the two-fluid theory can be used to predict the behavior of TES circuits reliably and hence they are valuable for assisting the design of sophisticated TES circuits.Comment: 10pages,11figures. Accepted to IEEE Trans. Appl. Supercon

    Temperature and loading-rate dependent critical stress intensity factor of dislocation nucleation from crack tip: Atomistic insights into cracking at slant twin boundaries in nano-twinned TiAl alloys

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    Fu R., Rui Z., Du J.P., et al. Temperature and loading-rate dependent critical stress intensity factor of dislocation nucleation from crack tip: Atomistic insights into cracking at slant twin boundaries in nano-twinned TiAl alloys. Journal of Materials Science and Technology 222, 290 (2025); https://doi.org/10.1016/j.jmst.2024.10.007.This paper investigates the temperature and loading rate dependencies of the critical stress intensity factor (KIC) for dislocation nucleation at crack tips. We develop a new KIC formula with a generalized form by incorporating the atomistic reaction pathway analysis into Transition State Theory (TST), which captures the KIC of the first dislocation nucleation event at crack tips and its sensitivity to temperature and loading rates. We use this formula and atomistic modeling information to specifically calculate the KIC for quasi-two-dimensional crack tips located at various slant twin boundaries in nano-twinned TiAl alloys across a wide range of temperatures and strain rates. Our findings reveal that twinning dislocation nucleation at the crack tip dominates crack propagation when twin boundaries (TBs) are tilted at 15.79° and 29.5°. Conversely, when TBs tilt at 45.29°, 54.74°, and 70.53°, dislocation slip becomes the preferred mode. Additionally, at TB tilts of 29.5° and 70.53°, at higher temperatures above 800 K and typical experimental loading rates, both dislocation nucleation modes can be activated with nearly equal probability. This observation is particularly significant as it highlights scenarios that molecular dynamics simulations, due to their time scale limitations, cannot adequately explore. This insight underscores the importance of analyzing temperature and loading rate dependencies of the KIC to fully understand the competing mechanisms of dislocation nucleation and their impact on material behavior

    β‐catenin deficiency in hepatocytes aggravates hepatocarcinogenesis driven by oncogenic β‐catenin and MET

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    Both activating and inactivating mutations in catenin β1 (ctnnb1), which encodes β-catenin, have been implicated in liver tumorigenesis in humans and mice, although the underlying mechanisms are not fully understood. Herein, we show that deletion of endogenous β-catenin in hepatocytes aggravated hepatocellular carcinoma (HCC) development driven by an oncogenic version of β-catenin (CAT) in combination with the hepatocyte growth factor receptor MET proto-oncogene receptor tyrosine kinase (MET). Although the mitogenic signaling and cell cycle progression was modestly impaired after CAT/MET transfection, the β-catenin-deficient livers displayed changes in transcriptomes, increased DNA damage response, expanded Sox9+ cells, and up-regulation of protumorigenic cytokines, including interleukin-6 and transforming growth factor β1. These events eventually exacerbated CAT/MET-driven hepatocarcinogenesis in β-catenin-deficient livers, featured by up-regulation of extracellular signal-regulated kinase (Erk), protein kinase B (Akt), and Wnt/β-catenin signaling and cyclin D1 expression. The resultant mouse tumors showed similar transcriptomes to human HCC samples with concomitant CTNNB1 mutations and MET overexpression.ConclusionThese data argue that while dominantly activating mutants of β-catenin are oncogenic, inhibiting the oncogenic signaling pathway generates a pro-oncogenic microenvironment that may facilitate HCC recurrence following a targeted therapy of the primary tumor. An effective therapeutic strategy must require disruption of the oncogenic signaling in tumor cells and suppression of the secondary tumor-promoting stromal effects in the liver microenvironment. (Hepatology 2018;67:1807-1822)

    Variations in incidence of venous thromboembolism in low-, middle-, and high-income countries

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    AimsTo examine the rates of venous thromboembolism (VTE) in high-income, upper middle-income, and lower middle/low-income countries (World Bank Classification).Methods and ResultsWe examined the rates of VTE in high-income, upper middle-income, and lower middle/low-income countries (World Bank Classification) in a cohort derived from four prospective international studies (PURE, HOPE-3, ORIGIN, and COMPASS). The primary outcome was a composite of pulmonary embolism, deep vein thrombosis, and thrombophlebitis. We calculated age- and sex-standardized incidence rates (per 1000 person-years) and used a Cox frailty model adjusted for covariates to examine associations between the incidence of VTE and country income level. A total of 215 307 individuals (1.5 million person-years of follow-up) from high-income (n = 60 403), upper middle-income (n = 42 066), and lower middle/low-income (n = 112 838) countries were included. The age- and sex-standardized incidence rates of VTE per 1000 person-years in high-, upper middle-, and lower middle/low-income countries were 0.87, 0.25, and 0.06, respectively. After adjusting for age, body mass index (BMI), smoking, antiplatelet therapy, anticoagulant therapy, education level, ethnicity, and incident cancer diagnosis or hospitalization, individuals from high-income and upper middle-income countries had a significantly higher risk of VTE than those from lower middle/low-income countries [hazard ratio (HR) 3.57, 95% confidence interval (CI) 2.40-5.30 and HR 2.27, 95% CI 1.59-3.23, respectively]. The effect of country income level on VTE risk was markedly stronger in people with a lower BMI, hypertension, diabetes, non-White ethnicity, and higher education.ConclusionThe rates of VTE are substantially higher in high-income than in low-income countries. The factors underlying the increased VTE risk in higher-income countries remain unknown.</div

    All‐In‐One OsciDrop Digital PCR System for Automated and Highly Multiplexed Molecular Diagnostics

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    Digital PCR (dPCR) holds immense potential for precisely detecting nucleic acid markers essential for personalized medicine. However, its broader application is hindered by high consumable costs, complex procedures, and restricted multiplexing capabilities. To address these challenges, an all‐in‐one dPCR system is introduced that eliminates the need for microfabricated chips, offering fully automated operations and enhanced multiplexing capabilities. Using this innovative oscillation‐induced droplet generation technique, OsciDrop, this system supports a comprehensive dPCR workflow, including precise liquid handling, pipette‐based droplet printing, in situ thermocycling, multicolor fluorescence imaging, and machine learning‐driven analysis. The system's reliability is demonstrated by quantifying reference materials and evaluating HER2 copy number variation in breast cancer. Its multiplexing capability is showcased with a quadruplex dPCR assay that detects key EGFR mutations, including 19Del, L858R, and T790M in lung cancer. Moreover, the digital stepwise melting analysis (dSMA) technique is introduced, enabling high‐multiplex profiling of seven major EGFR variants spanning 35 subtypes. This innovative dPCR system presents a cost‐effective and versatile alternative, overcoming existing limitations and paving the way for transformative advances in precision diagnostics

    Prognostic significance of glypican-3 in hepatocellular carcinoma: a meta-analysis

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    BACKGROUNDS: Glypican-3(GPC3) has been implicated in tumor development and progression for several years. However, the prognostic significance of GPC3 expression in patients with hepatocellular carcinoma (HCC) is controversial. We performed a meta-analysis of available studies to assess whether GPC3 can be used as a prognostic factor in patients with HCC. METHODS: We searched PubMed and Ovid EBM Reviews databases and evaluated the reference list of relevant articles for studies that assessed the prognostic relevance of GPC3 in patients with HCC. Meta-analysis was performed using hazard ratio (HR) or odds ratio (OR) and 95% confidence intervals (95% CIs) as effect measures. RESULTS: A meta-analysis of eight studies included 1070 patients was carried out to evaluate the association between GPC3 and overall survival (OS) and disease-free survival (DFS) in HCC patients. The relation between GPC3 and tumor pathological features was also assessed. Our analysis results indicated that high GPC3 expression predicted poor OS (HR: 1.96, 95% CI: 1.51–2.55) and DFS (HR: 1.99, 95% CI: 1.57-2.51) of patients with HCC. GPC3 overexpression was significantly associated with high tumor grade (OR: 3.30, 95% CI: 2.04–5.33), late TNM stage (OR: 2.26, 95% CI: 1.00–5.12), and the presence of vascular invasion (OR: 2.43, 95% CI: 1.23–4.82). CONCLUSIONS: GPC3 overexpression indicates a poor prognosis for patients with HCC, and it may also have predictive potential for HCC invasion and metastasis

    A novel and accurate predictor of survival for patients with hepatocellular carcinoma after surgical resection: the neutrophil to lymphocyte ratio (NLR) combined with the aspartate aminotransferase/platelet count ratio index (APRI)

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    BACKGROUND: The occurrence and development of hepatocellular carcinoma (HCC) depends largely on such non-tumor factors as inflammatory condition, immune state, viral infection and liver fibrosis. Various inflammation-based prognostic scores have been associated with survival in patients with HCC, such as the neutrophil/lymphocyte ratio (NLR), the platelet/lymphocyte ratio (PLR) and the prognostic nutritional index (PNI). The aspartate aminotransferase/platelet count ratio index (APRI) is thought to be a biomarker of liver fibrosis and cirrhosis. This study aims to evaluate the ability of these indices to predict survival in HCC patients after curative hepatectomy, and probe the increased prognostic accuracy of APRI combined with established inflammation-based prognostic scores. METHODS: Data were collected retrospectively from 321 patients who underwent curative resection for HCC. Preoperative NLR, PLR, PNI, APRI and clinico-pathological variables were analyzed. Univariate and multivariate analyses were performed to identify the predictive value of the above factors for disease-free survival (DFS) and overall survival (OS). RESULTS: Univariate analysis showed that NLR, PLR, PNI and APRI were significantly associated with DFS and OS in HCC patients with curative resection. Multivariate analysis showed that NLR and APRI were superior to PLR and PNI, and both were independently correlated with DFS and OS. Preoperative NLR >2 or APRI >1.68 predicted poor prognosis of patients with HCC after hepatectomy. Furthermore, the predictive range of NLR combined with APRI was more sensitive than that of either measure alone. CONCLUSIONS: Preoperative NLR and APRI are independent predictors of DFS and OS in patients with HCC after surgical resection. Higher levels of NLR or APRI predict poorer outcomes in HCC patients. Intriguingly, combining NLR and APRI increases the prognostic accuracy of testing
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